The present invention pertains to methods and apparatus for measuring multi-phase fluid flow such as mixtures of oil, water and gas utilizing a densimeter, a two-phase flow meter based on microwave attenuation characteristics and a mass or volumetric flow meter such as a modified coriolis-type flow meter.
Various techniques and systems have been developed for measuring multi-phase fluid flow, in particular, three phase fluid flow comprising a mixture of oil, water and gas. My U.S. Pat. No. 4,852,395, assigned to the assignee of the present invention describes a system for measuring multiphase fluid flow wherein gas is separated from a mixture of oil and water and the fractions of oil and water are then determined including measuring batch samples to correct for the residual gas content. Although such a system has a high degree of accuracy, it is relatively mechanically complex and requires a gas separator and gas flow meter.
Mechanically simple flow meters are sought for many applications, particularly in applications for measuring the multiphase fluid emanating from oil and gas wells wherein essentially, mixtures of water, hydrocarbon liquids, such as crude oil; and gas are continually produced in varying proportions of the total fluid flowstream. The present invention provides new and unique methods for measuring multiphase fluid flow, particularly of the type above described, as well as improved apparatus for measuring such multiphase fluid flow, which overcomes some of the problems associated with prior art methods and systems.